Tool-holder for engraving-machines.



No. 739,537.: PATENTED SEPT. 22, 1903.

A. B. FRANCIS.

TOOL HOLDER FOR BNGRAVINGMAGHINES.

* APPLIGATIDH iILEDJAK 29, 1903.

K0 MODEL.

cams rnzns m. wom-uma. wAsummn. n. c.

7 UNITED STATES Patented September 22, 1903.

PATENT OFFICE.

ALLAN FRANCIS, or CLEVELAND, 01-110.

SPECIFICATION forming part of Letters Patent No. 739,537, dated September 22, 1903.

Application filed January 29, 1903. fierial No. 141,078- (lilo model.)

To aZZ whom it may concern.-

Be it known that I, ALLAN ELFRANOIS, a citizen of the United States, residing at Cleveland, in the county of Cuyah'oga and State of Ohio, have invented a new and useful Improvement in Tool-Holders for Engraving- Machines, of which the following is a specification.

My invention relates to tool-holders for engraving-machines having rotary graverstocks. In such machines the graver-point must be centrally located in reference to the axis of the stock, and as it is necessary to use difierent gravers in different-kinds of work they must be frequently changed and must be so made that they can be readily attached and removed without being disturbed as to the position the graver occupies when adjusted for work. I attain these objects by the device illustrated in the accompanying drawings, in which- Figure 1 shows a finished holder. Fig. 2 shows a finished graver for the holder. Fig. 3 shows a perpendicular section of Fig. 1 made through its axis of rotation. Fig. 4 shows a sectional view of Fig. 1 made on a line with c c, as shown in Fig. 3.

D is the case that holds the other elements in their respective positions and by which the whole is attached to the arbor of the machine.

A cylinder of steel is machined into the peculiar form shown by D. It is threaded above for connecting it to the arbor, to which it is screwed up to the shoulder thereof, which always brings it in the same position. A hole smaller than the end of the arbor is driven to near its lower extremity and a countersink, hemispherical in form, is used to finish the end of the hole, making a socket in which the ball-like projection on the graver fits, allowing a ball-and-socket motion to a limited degree. By this action the graverpoint receives ample motion to compensate for any unavoidable inequality in grinding or any imperfection in the holderthat would cause it to require moving. Case D is provided with screw B for holding the graver down and with four centering-screws C CC C. Graver A is inserted from the top and is dropped into position, as shown in Fig. 3. The centering-screws, which were out far enough to give the graver access, are now brought in to touch the shank and screw B is brought down to it, but not so firmly as to bind it until after it has been centered by screws 0 O O C. The holder being now attached to the arbor of a machine, the usual test is made, and if the point is found to be at one side it can be quickly corrected by properly manipulating the screws to locate just where it should he, then the screw 13 is firmly driven and the graver is ready for use.

What I claim, and desire to secure by Letters Patent, is-

In engraving machine tool holders the combination of a case or a shell made as shown, being chambered in its lower portion for reception of a graver and having its inside constricted at lower end, to form a seat for the enlarged part of the graver to rest on; a graver consisting of a shank with aneulargement between it and the bit to rest in the seat of the shell; a screw to hold the 

